docs: update auth-ui.mdx (#21794)

Update auth-ui.mdx

Add instructions for the "view" prop and "sign_up" and "sign_in" values

Co-authored-by: Charis <26616127+charislam@users.noreply.github.com>

apps/docs/content/guides/auth/auth-helpers/auth-ui.mdx

@@ -470,3 +470,14 @@ Setting `showLinks` to `false` will hide the following links:
 - Already have an account? Sign in
 - Send a magic link email
 - Forgot your password?
+
+### Sign in and Sign up views
+
+Add `sign_in` or `sign_up` views with the `view` prop:
+
+```
+<Auth
+  supabaseClient={supabase}
+  view="sign_up"
+/>
+```